1. Field of the Invention
The present invention relates to lubricating compositions. The present invention further relates to methods of using the lubricating compositions, such as for high pressure metal-on-metal applications, for example, lubricating an engine.
2. Background of the Invention
Various lubricating compositions are known in the art. However, lubricants that have high boiling point, low freezing point, high viscosity index, good thermal stability, corrosion resistance, and/or high resistance to oxidation continue to be highly desired in the marketplace. Also desired are lubricating compositions that can have wide applications for different engines, machines, etc. and can perform well in different conditions.
There are different approaches described in the literature for improving the characteristics of a lubricant. Some of the approaches are directed to obtaining a base oil of special property for the lubricants. For example, U.S. Pat. No. 7,141,157 describes a process for preparing Fischer-Tropsch derived lubricating base oils; U.S. Pat. No. 6,824,671 describes poly-alpha-olefins having superior Noack volatility at low pour points. Some of the approaches are directed to providing a special additive component to the lubricants, such as an antioxidant, an anti-friction agent, an anti-wear agent, or a viscosity enhancer, etc. For example, U.S. Pat. No. 8,093,190 describes an antioxidant combination of a hindered amine and a metal compound; U.S. Pat. No. 7,018,962 provides a viscosity index (VI) improver concentrate; U.S. Pat. No. 5,723,419 discloses a composition with a chlorinated paraffin as an anti-friction agent; U.S. Pat. No. 7,615,519 discloses a composition comprising a hydrocarbon soluble titanium compound.
However, each of the above identified approaches has its own limitations. Thus, one objective of the present invention is to develop novel lubricating compositions that are superior to and/or more versatile than some of the existing lubricants.